Stencil screen and method of making the same



July 30, 1940. c. A. WULF STENCIL SCkEEN AND METHOD OF MAKING THE SAME Patented July 30, 194i;

UNITED s'lA'rE STENCIL SCREEN AND METHOD OF MAKING THE SAME Charles A. Wulf, Indianapolis, Ind.

Application October 17, 1936, Serial No. 106,201 (Cl. 41-385) 4 Claims.

An object of the invention is to provide a new and improved stencil screen, for reproducing designs accurately, and a cheap and reliable method of making the same. the stencil being of the type wire screen is preferred. Fig. 2 shows a detail section of wire screen readily available commercially, and hitherto considered suitable for use as a stencil screen. As shown in Fig. 2 the wires encountered in this process. This is lessened by that is produced photographically. l3 and I4 cross each other and so make the screen 5 Another object of the invention is to produce a twice as thick as the diameter of the wire from very thin stencil screen from the openings in which it is made. When such a screen is used, which the coloring material may be removed and th c l rin m r wi hin n opening through form the desired design accurately. the screen has a thickness of twice the diameter Another object of the invention is t0 provide f h Wire- Wh n ink is squeezed into a m h a cheap and reliable method of avoiding moir of h a stencil screen d removed p a efiects. face on which the design is to be formed, the ink Another object of the invention is to. increase Constitutes a p e Py that s 5 i811 in the accuracy and reliability with which in'terp p r i n t i base h it is likely to n and mediate shades of a design may be reproduced by ad. u ss t k or d si n-f n rial use of a screen stencil of proper character. is quite stifi.

Other objects and details of the invention will h pr rr w y f avoiding is iffi l y. is appear as the description proceeds, to iron the screen or run it through rollers to In the accompanying drawing, hi h forms a flatten it in the manner shown in Fig. 3. The part of t e ifi ation Figure 1 is a diagram wires 13 and Hi are flattened at ill on the outside 20 matic view of the phot ra hi r d ti of a of each intersection. As a result the thickness design upon a stencil screen; i 2 i an enlarged of the screen is reduced to but little more than detail section of a portion of a wire screen suitthat Of a Single W The blob f C i atable for use in making a stencil; Fig. 3 is a view transmitted through Such a Opening s O similar to Fig. 2 but showing the screen fl tt less height in proportion to its base, and is re- 25 or ironed to reduce its thickness; Fig. 4 is aplan moved from h op more sflv n l n yof a portion of the screen shown in section in The base of the blob in proportion o it height Fig. 3; Fig, 5 is a. diagrammatic enlarged detail is relatively increased so that there is much illustrating the action of light on the stencil less running Spreading 0f he pi e afte screen; Fig. 6 is a view of the finished screen porposit On the receiving u A a ons 30 tion resulting from th a tion shown i Fig 5; quence there is much less coalescing of the indi-, and Fig '7 i an enlarged plan of a more extem vidual deposits on the receiving surfaces before sive portion of a screen as actually formed in ac- Complete Setting o the P ent. c d ith thi invention A somewhat similar effect might be produced In Fig. 1 there is shown one conventional ar-- by Punching ho es in a thin sheet, or by weaving 35 rangement by which stencil screen patterns are flattened wires 01 ribbons in place of the usual produced photographically. In this view, there foundwiiesi but Obviously y uc e od of is a half tone transparency i0 having thereon a Dmd h Screen would be much more OSt Y positive of the pattern to be reproduced. Light, than merely ironing or flattening a wire screen '40 is passed through this transparency and falls upavailable on the market. 4%; on the light-sensitive material of stencil screen In the light flcliifln 0n the iight-senfiitive m filler of the screen is indicated. It will be readily It will be understood that the light pattern may understood that the openings between wires I3 be produced in any desired way, th ti l and M are tilled with light-sensitive material in. feature of the invention in this respect being the the usual manner The relative posit-ion 0f the 45 relation of the half-tone light screen to the stenlines of the usual light Screen, employed'in cil screen, as will be described below. Light rening pattern is indicated byiheavy dotted es dersinsoluble the light-sensitive material 'suffil1, and it Will be readily e stood that the ciently exposed thereto. After the desired exc o m light falls in Spots in t e Centers 0 posure, the stencil is soaked and washed to reof o Squares Outlined y lines 7 move the light-sensitive material not affected by As indicated in Fig. 5, the meshes of the stenthe light thus leaving portions of the screen open. cil screen are much finer than those of the li Design-forming material is pressed through these screen, A suitable proportion to use is ninety openings to form the desired pattern upon a lines to the inch on the light screen and two chosen surface. hundred and fifty wires to the inch in the stencil 55 The process thus 'far described has been in screen. Two good results are obtained by emprior use, and the present invention resides in ploying a. much finer mesh in the stencil than in details which constitute new and valuable imthe light screen. provements in the general process outlined above. Moir' effect is one of the recognized difficulties Wire of silk stencil screen may be used, but 50 screen; but when the same light screen has been used with 250 wire stencil, screen, moir effect has been greatly reduced. Therefore, a proportion of at least 2 to 1 between the meshes of the stencil and light screen is considered-critical in substantially eliminating molr eflects. When the stencil has at least 2 times as many meshes each way as the light screen, it has at least six times as many meshes in a given area.

The relatively fine mesh of the stencil screen also aids greatly in producting accurately shaded designs, particularly in reproducing wood grain and marble designs, where the grain and lines are indicated largely by different shades oi the same color.

In Fig. 5. there are indicated, for purposes of illustration, three light-afiected spots 20, 2| and 22 of diiferent diameters, in accordance with the amount of the light transmitted to the respective points, As indicated above, the design on the stencil is produced by the hardening by light of the material in. meshes subjected to the light, whereas the material insufficiently affected by light is washed out of the stencil screen, leaving openings through which coloring material may be forced. As will be seen from Fig. 6, the eflect of the three light-affected spots 20, 2| and 22 is to leave in the finished screen different numbers of screen meshes plugged with the hardened material. It is evident that the hardened material will be washed off with the dissolved material except where the hardened material extends to the wires, and that where only a fiap of hardened material is left, attached to a wire on one side, it is readily brushed off, and even if it clings to the wire until the first use of the stencil, the coloring matter pushes it aside. Consequently, the lighthardened material is eifective in pattern-forming only when it clings to at least two wires and the meshes of the final stencil are either completely open, completely closed, or sometimes half closed.

When the stencil mesh is about the same size as the light-screen mesh so that there is one light beam for each mesh of the stencil screen, most of the stencil meshes remain entirely open in the less affected portions of the stencil and entirely closed in the more affected portions. The result is that the reproduced design has less fine shading and more abrupt and sharp contacts than the original. As will be seen from Fig. 6, the relatively fine stencil screen makes possible the gradual increase in the number of squares in which the material is sufliciently hardened to remain, as the amount or light is increased. Where the maximum spread of a light dot is only one mesh, it can only leave the mesh open, closed, or half closed, making possible but three alternativea, Where a light dot may spread over eight or nine meshes, there is a possible variation of from one-half mesh by half-mesh stages up to the maximum of eight or nine meshes, making possible a very gradual shading from light to dark.

A fine-meshed stencil screen made in this improved way has a multiplicity of spots of lighthardened material thereon, each spot covering from one-half a mesh up to a plurality of meshes, and is thus distinguished from a screen where each light dot affected only one mesh.

Fig. 7 is a reproduction of an enlarged view of a small section of a screen produced in the manner described. In this view it will be seen that the areas affected by the light beams vary from 1%., meshes to four meshes of the screen. It will be readily seen that a similar gradual variation will extend to an area on the one hand where all meshes are filled to an area on the other hand where all are open.

The commercial fine-meshed screen is made of finer wire than coarser screen, and the fiattening of the screen as shown in Figs. 3 and 4 further reduces the effective thickness of the blob of material deposed by each open mesh. Also the flattened screen provides a more nearly continuous margin for each mesh and adds to the reliability with which the light hardened material remains attached to the wire and therefore cooperates with the relatively finemeshed elfect to produce very accurate reproductions of designs comprising different shadings.

While, as will be noted by comparing Figs. 5 and 6, some of the hardened material may be lost from each of spots 20, 2| and 22,50 that the reproduction is not microscopically accurate, no

dot of any appreciable size is entirely lost, and the loss on different dots so nearly evens up on the average that any difference between the original halt tone design and the final design applied by the stencil is not noticeable to the naked eye.

As indicated above, this invention is peculiarly effective when employed to reproduce wood graining or marbling, but it will be readily understood that it may be employed for other purposes where similar eifects are desired, and that departures, obvious to those skilled in the art, may be made from the exact process, proportions and construction disclosed: within the terms of the appended claims.

What I claim is:

1. A stencil screen comprising open-meshed woven round wire flattened at the intersections and certain of the meshes being closed to form a desired design.

2. A stencil screen comprising open-meshed woven round wire flattened at the intersections and having spots of light hardened material thereon, said spots varying from not more than one mesh to at least three meshes in extent, whereby a gradually shaded design may be produced.

3. A stencil screen comprising open-meshed woven round wire flattened at the intersections and having spots of light hardened material thereon, said spots varying from not more than one mesh to at least six meshes in extent, whereby a gradually shaded design may be produced.

4. A method of forming a stencil screen from fine meshed woven wire, which consists in fiattening the intersections of the wires, filling the openings of the meshes with a soluble material capable of being rendered insoluble by light, passing light, in a half tone pattern materially coarser than the wire meshes, onto said material and thereby rendering portions of said material insoluble in a pattern corresponding with said light pattern, and then washing away the still soluble portion or said material.

CHARLES A. WULF. 

